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LL-37

Also known as

Cathelicidin LL-37 · Cathelicidin antimicrobial peptide · hCAP-18 fragment · CAP-18 C-terminal peptide · hCAP18-derived peptide · Ropocamptide (investigational topical designation / Promore Pharma) · LL37 · LL 37 · Human cathelicidin · FALL-39 (historical related designation talk)

Community talk. May be wrong. Not medical advice. Not a protocol. Not for human or animal use.

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Peptide Lots of talk Mixed SubQ / Topical Immune peptides

Mixed — human trials used topical ulcer gel; community infection and immune use is usually SubQ, and those routes are not interchangeable.

What people say LL-37 is the human cathelicidin antimicrobial peptide. Its strongest human intervention evidence is topical venous-ulcer gel, while community infection and immune use is usually unstudied SubQ product use. Doses people talk about
Vague same-author recollection~125 mcg/day; route not stated

The author recalled the amount imprecisely across roughly 30-day cycles and extensive co-treatment; 5 mg referred to a reported cycle/course total, not a dose or vial total.

Protocol-page SubQ band~100–250 mcg once daily SubQ

Frequently repeated chart range, not a human trial or verified product exposure.

Phase IIb topical concentrations0.5 or 1.6 mg/mL topical gel

Ropocamptide was applied to venous leg ulcers with compression for up to 13 weeks; this is a distinct local formulation.

Community products were unverified, and topical mg/mL gel concentrations do not convert into SubQ microgram amounts.

Half-life & effect duration

Half-life in the body
  • Mouse-plasma stability testAbout 242 minutes — roughly 4 hours
  • Under-the-skin injectionNo settled estimate
Felt duration people report
  • Early Lyme accountsFlu-like reactions over the first few doses or 3–4 days
  • Later accountsPartial benefit, with symptoms returning after stopping
Timing context & sources
How it may feel Community reports include flu-like or “herx” symptoms in the first few doses and partial improvement without cure. A separate SIBO thread supplied theory and non-use discussion, not an LL-37 outcome; co-treatments, unstated routes and vague amounts dominate.
Cycles people discuss Community courses range from two to four weeks to longer repeated blocks, while human topical trials used clinic-managed twice-weekly dressing schedules. These route-specific calendars are not interchangeable. Timing Topical use follows dressing changes, while systemic community use is framed as a short antimicrobial block rather than a pre-workout or daily Glow add-on. Morning placement appears as convenience lore, not pharmacokinetic proof. Stacks Lyme and immune reports commonly combine LL-37 with thymosin alpha-1, KPV, herbs, antibiotics, infusions or other peptides. Those combinations make microbial and symptom attribution especially weak. Access talk April 2026 Category 2 off: Coming off the do-not-compound bucket is not Category 1, not 503A placement, and not FDA approval. Labs people mention No LL-37 blood level: People judge itch/wheal, ‘immune noise,’ and the infection story — not a peptide concentration. Watch for Topical trial safety ≠ injectable safety: VLU RCTs reported acceptable local/systemic AE profiles for gel + compression; that does not prove daily systemic subQ is safe long-term.
Related
KPVBPC-157TB-500GHK-Cu

Tap a line to jump into the full notes. Research only — may be wrong.

Timing context & sources

Half-life in the body

No human SubQ concentration-time study was identified; a 242 ± 45-minute mouse-plasma incubation result is laboratory stability, not human PK.

Topical wound-gel schedules and community daily injections cannot be used to infer systemic half-life.

Laboratory matrix, species and formulation differ; the bounded search does not establish universal absence of unpublished or inaccessible data.

Felt duration people report

Lyme reports described flu-like reactions for the first few doses or three to four days, partial benefit without cure and recurrence after stopping; the SIBO thread did not supply an LL-37 use outcome.

One same-author account spanned several cycles over months with herbs, infusions and other peptides; its 2026 amount reply did not state route. Another user lowered an unspecified amount after early symptoms.

Self-defined “herx” language is not evidence of microbial killing; products, routes, amounts and outcomes were generally unverified and heavily confounded, and the SIBO discussion had no LL-37 exposure.

  • r/Lyme — Any experience with LL-37 peptide? (opens in a new tab)Multiple-author thread: one author first described three cycles across roughly six months, but later described three 5 mg cycle/course totals spread across one year and then vaguely recalled roughly 30-day cycles at about 125 mcg/day; no route was stated. The author also reported stronger “herx” and improved live-blood tests while listing extensive herbs, infusions and other peptides. A separate user reported early reactions after two doses and lowering an unspecified amount.Retrospective multi-author discussion with conflicting six-month versus one-year chronology, vague amount memory, unstated route, nonvalidated live-blood testing, unverified product and extensive co-treatment; “herx” does not establish antimicrobial efficacy.
  • r/Lyme — Anyone try LL-37 cathelicidin peptides? (opens in a new tab)Visible same-author account describes flu-like or low-fever symptoms for the first three to four days, perceived partial benefit but no cure, and multiple simultaneous peptides and supplements. Other replies report benefit without clearance and symptom return after stopping three to four months of use.Unverified products and diagnoses, no amounts or objective outcomes, multiple co-agents and retrospective follow-up.
  • r/SIBO — LL-37 peptide to kill SIBO (opens in a new tab)Thread contains theory and copied protocols. One commenter says other peptides they used regularly had little SIBO effect, then separately says they had not seen LL-37 success reports; the original poster later confirms they did not use LL-37.Sparse theory, hearsay and non-use discussion; no LL-37 exposure, verified product, amount, route, breath-test outcome or treatment comparison.

What people say 8

  • Community injectable narratives: Stubborn skin issues, sinus load, gut “bug” talk, general immune support, and “chronic infection” logs — multi-agent confounds (antibiotics, binders, sleep, concurrent peptides) make single-agent credit hard. forumanecdote
  • Lyme / mold / biofilm forum volume: Very high anecdote density for biofilm-busting and co-infection stacks; no controlled human injection trials for Lyme disease, CIRS, or mold illness labels. anecdoteforum
  • Vitamin D / endogenous production: Supporting natural CAMP expression via adequate 1,25-dihydroxyvitamin D is frequently framed as complementary or foundational vs exogenous peptide alone. trialforum
  • What people do not have trial proof for (injected): Stand-alone cure of chronic Lyme, systemic biofilm clearance, guaranteed gut remodel, or transfer of topical ulcer RCT effect sizes to daily subQ. trialforum
  • Three jobs people mix up (2025–26): Topical wound gel (the only human RCT lane), SubQ ‘immune/Lyme/mold/CIRS’ pins, and lower-mcg gut/SIBO talk. r/SIBO 2025–26 logs are mixed-to-null on ‘LL-37 killed my SIBO’; r/Lyme still runs short cycles in TA-1 stacks. Those routes are not interchangeable with VLU gel. forumtrial
  • Anti-biofilm (preclinical): Prevents biofilm formation and can disrupt established biofilms at concentrations often below classic MICs in model systems (e.g. Pseudomonas, Staphylococcus) — core rationale for chronic-infection forum interest. labanimal
  • Wound biology: Linked to re-epithelialization, keratinocyte migration, angiogenesis, and chronic-ulcer expression deficits (LL-37 often low/absent in chronic venous/diabetic ulcer epidermis vs healthy skin). animaltrial
  • Antimicrobial (lab): Broad in-vitro activity discussed vs many Gram-positive and Gram-negative bacteria, some fungi, and selected viruses; membrane-disruption + immunomodulation dual framing. lab

Doses people talk about 12

  • Observed amount recollection and separate charted SubQ amounts: One same-author Lyme account vaguely recalled ~125 mcg/day, without stating the route; protocol pages separately repeat ~100–250 mcg SubQ once daily. The same report's 5 mg referred to a reported cycle/course total, not a dose or vial total. forum
  • Conservative start talk: ~100–200 mcg/day (some charts start ~50–100 mcg and titrate by ~50 mcg steps weekly as tolerated). forum
  • “Standard chart” 125 mcg: Multiple peptide-protocol sites list ~125 mcg subQ daily as a simple fixed dose (sometimes for multi-week or ~50-day structures). forum
  • Advanced / upper community range: Up to ~500 mcg/day appears in advanced/clinic-style posts; more injection-site irritation and systemic immune-noise talk at the high end. forum
  • Wider educational charts: Some 5 mg vial guides span ~50–400 mcg daily with gradual titration — still informal. forum
  • Frequency variants: Once daily is default; 5 days on / 2 days off (weekday-style) is common; every-other-day variants also appear for tolerability or cost. forum
  • Schedule length (injectable talk): Most repeated short block = ~2–4 weeks; some vendor protocols push continuous daily for ~50 days then multi-week off; longer 8–12 week “research course” charts exist but are less universal and still unvalidated. forum
  • Gut vs immune charts (2025–26): SIBO/gut threads often copy ~100 mcg daily; Lyme/infection stacks talk the higher 100–250+ mcg immune band. Topical ulcer mg/mL is a different product class. forum
  • Body-weight claims: Typical bro charts use flat mcg, not mg/kg; occasional clinic/video “mcg per kg” figures diverge wildly from the 100–500 mcg consensus and should be treated as non-standard outliers, not the default research-peptide culture. forum
  • Purity / fill flag: Gray-market labeled mcg may not equal delivered active peptide; TFA-salt and net-peptide % notes in lab contexts further separate “vial label” from true mass. forumlab
  • Morning timing lore: Some charts prefer AM injection for “immune day” framing — convenience more than PK proof. forum
  • Framing: Injectable ranges in this section are community/clinic-discussion structure for research-use product talk — not medical advice, not FDA-validated injection protocols, not equivalent to topical ulcer gel. forum

How it may feel 8

  • First doses to days 3–4 (community reports): Some users describe flu-like or “herx” symptoms, while others report little; routes, amounts and co-treatments are often unclear, and this is not proof of microbial killing. forum
  • Week 1: Watching infection/skin/sinus “load” vs inflammatory flare; no validated injectable response curve — some report nothing, some report local reactivity that settles. forum
  • Weeks 2–4: Reports remain mixed: one user lowered an unspecified amount after early symptoms, and another described benefit without cure. A separate SIBO thread contained theory and non-use discussion, not an LL-37 treatment outcome. forumanecdote
  • Extended vendor charts (e.g. ~50-day daily runs): Described in protocol blogs; still community structure, not a trial-validated systemic course — late-cycle gains harder to attribute. forum
  • Post-block: Some report residual improvement; others rebound if the underlying driver (biofilm niche, venous disease, mold exposure, immune dysregulation) remains. anecdote
  • Early-reaction culture: Community talk generally favors dose cut, slower push, antihistamine discussion, or stop — not progressive escalation through building hives/flu-like feels. forum
  • If nothing by end of a short block: Forums often reassess diagnosis, concurrent antimicrobials/wound care, product authenticity, and whether expectations wrongly mapped topical RCT results onto injection. forum
  • Topical trial timeline: Multi-week twice-weekly dressing applications with wound-area endpoints (4-week treatment phase in first-in-man; 13-week treatment in Phase IIb) — not a daily subQ feel schedule. trial

Around the dose 5

  • Clock: Depends on the job — topical wound charts follow dressing changes; systemic research-chem talk is not a pre-workout. forum
  • After: For skin/wound talk, clean care and not picking the site. For systemic DIY talk, people treat it as higher-caution, not a daily Glow add-on. forum
  • Pick a job (2025–26): Topical dressing ≠ belly pin for ‘bugs.’ Gut/SIBO logs often go slower/lower because die-off/herx stories are loud. forum
  • Not a Glow add-on: Lyme/CIRS/SIBO threads treat it as a short antimicrobial block, often next to TA-1, KPV, or binders — not a recovery peptide. forum
  • If it itches or wheals: Community still cuts dose or stops rather than pushing a ‘herx.’ Mast-cell biology is the usual explanation, not proof it is ‘working.’ forum

Cycles people discuss 9

  • Short block (most common community structure): ~2–3 weeks on, then ≥2 weeks off. forum
  • Standard block: ~4 weeks on, often 2–4 weeks off — upper end of typical injectable write-ups. forum
  • 50-day continuous charts: Some protocol blogs advertise 125 mcg daily × ~50 days then ~4 weeks off — vendor/community structure, not a published systemic RCT schedule. forum
  • Pulsed washout charts (example pattern discussed): e.g. ~4 weeks on → ~2 weeks washout → another ~4 weeks on → washout — one style of “immunomodulation research” calendar, not validated. forum
  • Extended clinic-style talk: 8–12 weeks (occasionally longer) appears in some educational vial protocols with slow titration — still anecdote/clinic convention. forum
  • Pulsed flares: Short runs around infection/skin flares more common than indefinite year-round daily use among cautious posters. forum
  • Why off periods: Immune-load / inflammation double-edge caution and lack of long-term systemic safety database — not a PK-driven washout proven in humans for injectables. forum
  • Re-runs: Restarting after off periods is described anecdotally; long-term repeated systemic safety is not established. forum
  • Topical trials: Multi-week twice-weekly dressing under clinical supervision (4-week randomized phase first-in-man; 13-week treatment Phase IIb) — not a DIY injection template. trial

Timing 7

  • Human subQ PK gap: No reviewed human concentration-time study establishes LL-37 half-life after gray-market subcutaneous use; daily schedules are community convention, not a measured depot or clearance result. trialforum
  • No human subQ PK package: Published human trial work is topical wound gel; daily injectable frequency is community logic from short duration + immune signaling lore, not gray-market PK studies. trialforum
  • After levels fall: Immune/wound signaling and downstream cellular effects may outlast free peptide — used to justify not chasing continuous plasma levels, but not a personal guarantee. forumanimal
  • Ex vivo plasma context: One mouse-plasma incubation study measured LL-37 half-life at 242 ± 45 minutes; this is an in-vitro stability assay, not human subQ PK or a nanocarrier depot value. lab
  • Model dependence: Serum, plasma, wound fluid and engineered carriers produce different stability results; no reviewed cellular model establishes a universal 3–6-hour human half-life. lab
  • Topical cadence logic: Twice-weekly gel matched dressing-change intervals and local wound-bed exposure, not systemic depot PK. trial
  • Wound-fluid binding: Literature notes protein binding in wound fluid may partially protect peptide from proteases — relevant to topical wound context more than abdominal subQ. triallab

More on what it is 9

  • Why people care: High-volume forum and clinic talk for infection, biofilm, wound/skin, gut, Lyme/mold-adjacent, and “innate immune support” — plus real (but narrow) human topical ulcer RCTs. forumtrial
  • Not: Not an FDA-approved systemic antibiotic; not a BPC-157/TB-500-style recovery peptide; not interchangeable with KPV or thymosin alpha-1. trialforum
  • Research lens: Gray-market “protocol charts” and Lyme/mold cure narratives are discussion artifacts until matched to route, product verification, and named human evidence. forum
  • What it is: The only human cathelicidin antimicrobial peptide (AMP) — a 37–amino-acid C-terminal fragment of the precursor hCAP-18 encoded by the CAMP gene; sequence commonly listed as LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES; MW ~4.5 kDa (~4493 Da). trial
  • Also called: Cathelicidin LL-37, CAP-18 fragment, hCAP-18-derived peptide; investigational topical drug name ropocamptide (Promore Pharma). trial
  • Mechanism talk (plain): Amphipathic cationic α-helix that disrupts microbial membranes; binds LPS/endotoxin; recruits/modulates immune cells (FPR2 and related receptor talk); anti-biofilm at sub-MIC levels in lab work; supports keratinocyte migration, angiogenesis, and re-epithelialization in wound biology. labanimal
  • Double edge: Same pathways can amplify inflammation — LL-37 complexed with self-DNA/RNA is a documented driver of type I interferon pathways in psoriasis and SLE literature; excess/abnormal processing is central to rosacea models. trial
  • Evidence honesty: Strongest human data = topical hard-to-heal venous-leg-ulcer RCTs; no published human RCTs of daily subcutaneous injection for systemic infection or immune goals. trial
  • Endogenous link: CAMP/LL-37 expression is vitamin-D–inducible (VDR/VDRE on the CAMP promoter) — basis for “optimize vitamin D first” stack talk. trial

Stacks 9

  • Immune “defense trio” (very common clinic/forum cluster): LL-37 + Thymosin Alpha-1 + KPV — framed as antimicrobial (LL-37) + immune modulation (TA1) + inflammation calm (KPV); multi-agent confounds dominate outcome stories. forum
  • LL-37 + Thymosin Alpha-1 (without KPV): Infection/immune forum pairing when people want antimicrobial + T-cell/innate support narratives without the anti-inflammatory fragment. forum
  • Gut / barrier talk: Sometimes with KPV (and/or BPC-157) in GI and “leaky gut + bug load” threads — attribution is murky. forum
  • Infection + tissue repair: Stacked with BPC-157 and/or TB-500 / TB-4 when the story is “clear microbes + heal tissue” (e.g. stubborn soft-tissue with suspected infection). forum
  • Skin / copper-peptide adjacency: Occasional GHK-Cu co-discussion for skin repair aesthetics — different mechanism class; not a fixed ratio blend. forum
  • Endogenous support: Vitamin D (and sometimes lifestyle sun/sleep basics) framed as supporting natural CAMP/cathelicidin expression rather than replacing exogenous peptide. forumtrial
  • Vs pure recovery stacks: Not a Wolverine (BPC+TB) or GLOW (BPC+TB+GHK-Cu) core component; people add it when antimicrobial/immune is the goal, not pure soft-tissue repair. forum
  • Ratio honesty: Pre-mixed “immune blends” vary by vendor; separate vials keep each peptide’s mcg math clear. forum
  • Foundational confounds: Wound care, compression (for VLUs), culture-directed antimicrobials, mold remediation, sleep, and nutrition often share credit in “it finally cleared” logs. forum

Access talk 6

  • April 2026 Category 2 off: Coming off the do-not-compound bucket is not Category 1, not 503A placement, and not FDA approval. trialforum
  • Topical trial ≠ vial shop: Ropocamptide/HEAL LL-37 gel was the human VLU RCT product. 2026 forum buy talk is still RUO lyophilized vials for SubQ. trialforum
  • How people talk about getting it: Gray research vials and occasional clinic ‘immune’ charts. A not-for-human-use label is not QC. forum
  • Not on the July 2026 seven: BPC/KPV/TB-500/MOTS-c/Epitalon/Semax/DSIP were the July 23–24 PCAC peptides. LL-37 was not in that room. trial
  • Next PCAC window: FDA has said another committee meeting before the end of February 2027 will discuss cathelicidin (LL-37) with GHK-Cu, Dihexa acetate, Melanotan II, and PEG-MGF. Advisory, not a product launch. trial
  • Why compounding talk is cautious: FDA safety-risk writeups cite immunogenicity for some routes plus peptide-impurity / API-characterization complexity. trial

Labs people mention 3

  • No LL-37 blood level: People judge itch/wheal, ‘immune noise,’ and the infection story — not a peptide concentration. forum
  • Vitamin D adjacency: Endogenous CAMP/LL-37 is vitamin-D–inducible, so 25-OH D shows up as a ‘do this first’ lab in immune threads. trialforum
  • Inflammation labs (optional): hs-CRP appears in generic 2026 peptide-monitoring posts; not a specific LL-37 marker. forum

Storage notes 2

  • No mix instructions here: STUDresearch does not list reconstitution, diluent volumes, or syringe unit charts. People reconstitute many different ways and vial labels differ — that content creates more confusion than clarity. forum
  • Storage (general talk only): Unopened research products are usually kept cool, dry, and away from light per the seller label. Anything after first use is product-specific — follow the label, not a universal forum SOP. forum

Watch for 13

  • Injection site (most common subQ report): Redness, burn, swell, itch, wheal/flare — often within minutes to hours; resolves in many logs within ~24–48 h. forum
  • Systemic noise: Flushing, warmth, flu-like malaise, or “immune hangover” in a subset — more often discussed at higher mcg or in sensitive users. forumanecdote
  • Pregnancy / lactation / heavy immunosuppression: Essentially no safety database for research-peptide injection in these contexts — community and educational sources flag avoidance without specialist oversight. forum
  • Stop signals discussed: Spreading hives, progressive flu-like escalation, new autoimmune-skin flares, or severe injection-site reactions — dose-cut or discontinue culture rather than push through. forum
  • Not a substitute for workup: Fever, progressive infection, non-healing ulcers, and systemic illness still need medical evaluation; peptide anecdotes are not culture-directed therapy. forumtrial
  • Gut/SIBO honesty (2025–26): r/SIBO still asks ‘has anyone actually cleared SIBO with LL-37?’ Replies are sparse; several long-time posters say they have not seen a clean win. Die-off/herx stories are not a breath-test cure. forum
  • Mast-cell / histamine mechanism: LL-37 is a documented mast-cell activator (histamine, PGD2 pathways; MRGPRX2 agonist framing in modern write-ups) — explains first-dose local reactivity independent of classic IgE allergy. labtrialforum
  • Psoriasis: Excess LL-37 and LL-37–self-nucleic-acid complexes are central to psoriasis pathogenesis literature; exogenous use is flagged as a theoretical flare risk in psoriasis-prone people. trial
  • Rosacea: Abnormal cathelicidin processing and LL-37 fragments drive rosacea-like inflammation in models; repeated LL-37 administration induces rosacea-like lesions in animals; community caution for rosacea-prone skin. animaltrial
  • Lupus / type I interferon: LL-37 complexed with self-DNA/RNA promotes pDC TLR9/TLR7 activation and type I IFN pathways implicated in SLE — major “not a free immune booster” flag. trial
  • NLRP3 / inflammasome talk: Repeated LL-37 exposure linked to inflammasome-pathway activation in skin research — another inflammation double-edge note. trial
  • Host cytotoxicity (concentration-dependent): High local concentrations damage host cells (RBCs, lymphocytes, fibroblasts) in vitro; literature often places antimicrobial/chemotactic effects in roughly ~0.1–10 μM ranges and stronger cytotoxicity above ~10 μM — supports “more isn’t better.” lab
  • Topical trial safety ≠ injectable safety: VLU RCTs reported acceptable local/systemic AE profiles for gel + compression; that does not prove daily systemic subQ is safe long-term. trial

Updated: 2026-09-01

Evidence mix Mixed trial + community tags Full: every bullet (trial + community). Use Scan for a faster bro-science read.
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